Modification of biological properties of biodegradable polyurethane
scaffolds for tissue engineering with long-chain plant polyprenols
Krystyna Walinska (1), Anna Iwan (2), Katarzyna Gorna (3), Sylwester Gogolewski (3)
(1) Department of Biology, Institute of Biotechnology and Environmental Sciences, University
of Zielona Gora; Zielona Gora, Poland, (2) Department of Histology and Embryology,
Center of Biostructure Research, Medical University of Warsaw, Warsaw, Poland;
(3) Polymer Research, AO Research Institute, Davos, Switzerland
Biodegradable, biocompatible polyurethanes are promising candidates for a number of
implantable devices. Scaffolds for tissue repair and regeneration are examples. These scaffolds
have shown an excellent interaction with biological cells and tissues. Modification of the scaffold
with biologically active substances can additionally enhance the cell-material interaction. Among
pharmacologically active substances under consideration are plant polyprenols (long-chain
isoprenoid alcohols). Plant polyprenols do not invoke teratogenic, embryotoxic, mutagenic,
carcinogenic, allergenic and immunotoxic effects and do not harmfully affect the functions of the
endocrine system, i.e. they fulfil the requirements for materials for implantable devices.
This pilot study aimed in assessing whether impregnation of the microporous biodegradable
polyurethane scaffolds with long-chain polyprenols has beneficial effects on their interaction with
chondrocytes.
Experimental: Aliphatic polyurethane was based on poly(-caprolactone) diol (MW=530 Da)
and biologically ative 1,4:3,6-dianhydro-furo(3,2-b)furan-3,6-diol [1,2]. Microporous scaffolds:
Prepared using a combined salt-leaching-phase-inverse technique [2]. As-prepared scaffolds were
used as control to compare with those impregnated with polyprenols. Long-chain polyprenols: A
mixture of prenol-10 and prenol-11 isolated from leaves of Magnolia Cobus. Chondrocytes:
Isolated from the articular-epiphyseal cartilage of leg bones of 5 days old inbred LEW rats seeded
at density of 250,000 cells per each scaffold sample. Culture time 2 and 5 weeks.
Characterization techniques: Size exclusion chromatography, differential scanning calorimetry,
gravimetry, scanning electron microscopy, infrered spectrometry, water permeation.
Results and Conclusions: Polyurethane scaffolds had interconnected pores with an average size
in the range of 5 - 100 m. The mixture of long-chain polyprenols (decaprenol and undecaprenol)
exhibited two thermal transitions at temperatures in the range of 35.5 to 39.7oC which were
assigned to the crystal-crystal transition. The high-energy transition at 38.0oC with ΔH=3.55 J/g
results from the gel-to-liquid crystal transition and/or the solid-to-mesophase transition of
polyprenol molecules. The IR spectra of the polyurethane showed absorption bands characteristic
for these class of compounds, i.e. (C=O) (amide I), δ(NH) and (CO-N) (amide II) and (C=O)
typical for polyster. The polyprenol showed the absorption bands assigned to the methylene -CH3
groups and the -C=C- groups which are specific for this class of compounds. Infrared spectrum of
polyurethane scaffolds impregnated with polyprenols showed one absorption band at 1376 cm -1
assigned to methylene group originating exclusively from polyprenols. Polyurethanes support
attachment and growth of rat chondrocytes. The cells invaded the pores of the scaffolds,
maintained round morphology and produced abundant fibrillar extracellular matrix resembling the
network formed by chondrocytes in vivo. Impregnation of the membranes with biologically active
amphiphylic polyprenols seems to facilitate the cell - material interaction. Further quantitative
studies are required to verify to which extent this interaction is affected by the presence of the
polyprenols in the scaffold. In addition is should be determined whether prenols chemistry and
molecular weight affects the type of interaction e.g. the cell attraction or repellence. This is of
particular significance as the first effect could be exploited to enhance interaction of tissue repair
scaffolds with cells while the second effect might be utilized in designing tissue adhesion barriers.
References: 1. Gorna K, Gogolewski S, Polymer Degradation & Stability, 79, 475-485(2003); 2. Gorna K, Gogolewski S, J
Biomed Mater Res, 2006, in press.
Keywords: Polyurethane scaffolds, polyprenols, tissue engineering, chondrocytes, cell culture